Document
Freescale Semiconductor Data Sheet: Technical Data
An Energy Efficient Solution by Freescale
Document Number: MPR121 Rev. 4, 02/2013
Proximity Capacitive Touch
Sensor Controller
The MPR121 is the second generation sensor controller following the
initial release of the MPR03x series of devices. The MPR121 features an increased internal intelligence plus Freescale’s second generation capacitance detection engine. Some major enhancements include an increased electrode count, a hardware configurable I2C address, an expanded filtering system with debounce, and completely independent electrodes with built-in autoconfiguration. The device also features a 13th
simulated electrode which represents the simultaneous charging of all the electrodes connected together. When used with a touch panel or touch screen array, the 13th simulated electrode allows a greater near proximity
detection distance and an increased sensing area.
Features
• 1.71V to 3.6V operation • 29 μA typical run current at 16 ms sampling interval • 3 μA in scan stop mode current • 12 electrodes/capacitance sensing inputs in which 8 are
multifunctional for LED driving and GPIO • Integrated independent autocalibration for each electrode input • Autoconfiguration of charge current and charge time for each
electrode input • Separate touch and release trip thresholds for each electrode,
providing hysteresis and electrode independence • I2C interface, with IRQ Interrupt output to advise electrode status
changes • 3 mm x 3 mm x 0.65 mm 20 lead QFN package • -40°C to +85°C operating temperature range
Implementations
• General Purpose Capacitance Detection • Switch Replacements • Touch Pads, Touch Wheel, Touch Slide Bar, Touch Screen Panel • Capacitance Near Proximity Detection
Typical Applications
• PC Peripherals • MP3 Players • Remote Controls • Mobile Phones • Lighting Controls
Device Name MPR121QR2
Temperature Range -40°C to +85°C
ORDERING INFORMATION
Case Number
Touch Pads
2059 (20-Pin QFN)
12-pads
MPR121
Bottom View
20-PIN QFN CASE 2059-01
Top View
VDD ELE11 ELE10 ELE9 ELE8
20 19 18 17 16
IRQ SCL SDA ADDR VREG
1 2 3 4 5
15 ELE7 14 ELE6 13 ELE5 12 ELE4 11 ELE3
6 7 8 9 10
VSS REXT ELE0 ELE1 ELE2
Pin Connections
I2C Address 0x5A - 0x5D
Shipping Tape & Reel
© 2009-2011, 2013 Freescale Semiconductor, Inc. All rights reserved.
1 Pin Descriptions
Table 1. Pin Descriptions
Pin No. Pin Name
Description
1 IRQ Open Collector Interrupt Output Pin, active low
2
SCL
I2C Clock
3
SDA
I2C Data
4
ADDR
I2C Address Select Input Pin. Connect the ADDR pin to the VSS, VDD, SDA or SCL line, the resulting I2C addresses
are 0x5A, 0x5B, 0x5C and 0x5D respectively
5 VREG Internal Regulator Node – Connect a 0.1 μF bypass cap to VSS
6 VSS Ground
7 REXT External Resistor – Connect a 75 kΩ 1% resistor to VSS to set internal reference current
8 ELE0 Electrode 0
9 ELE1 Electrode 1
10 ELE2 Electrode 2
11 ELE3 Electrode 3
12 ELE4 Electrode 4
13 ELE5 Electrode 5
14 ELE6 Electrode 6
15 ELE7 Electrode 7
16 ELE8 Electrode 8
17 ELE9 Electrode 9
18 ELE10 Electrode 10
19 ELE11 Electrode 11
20 VDD Connect a 0.1 μF bypass cap to VSS
MPR121 2
Sensors Freescale Semiconductor, Inc.
2 Schematic Drawings and Implementation
VDD 1.71V to 2.75V
0.1 μF GND
20 VDD
6 VSS
5 VREG
1 IRQ
2 SCL
3 SDA
4 ADDR
7 REXT
75 kΩ 1%
ELE11/LED7 ELE10/LED6
ELE9/LED5 ELE8/LED4 ELE7/LED3 ELE6/LED2
ELE5/LED1 ELE4/LED0
ELE3 ELE2 ELE1 ELE0
19 18 17 16 15 14 13 12
11 10 9 8
GND
MPR121Q TOUCH SENSOR
Figure 1. Power Configuration 1: MPR121 runs from a 1.71V to 2.75V supply.
VDD 2.0V to 3.6V
0.1 μF
0.1 μF
GND
GND
20 VDD
6 VSS
5 VREG
1 IRQ
2 SCL
3 SDA
4 ADDR
7 REXT
75 kΩ 1%
ELE11/LED7 ELE10/LED6
ELE9/LED5 ELE8/LED4 ELE7/LED3 ELE6/LED2
ELE5/LED1 ELE4/LED0
ELE3 ELE2 ELE1 ELE0
19 18 17 16 15 14 13 12
11 10 9 8
GND
MPR121Q TOUCH SENSOR
Figure 2. Power Configuration 2: MPR121 runs from a 2.0V to 3.6V supply.
MPR121 3
Sensors Freescale Semiconductor, Inc.
3 Device Operation Overview
Power Supply
The VDD pin is the main power supply input to the MPR121 and is always decoupled with a 0.1 μF ceramic capacitor to the VSS. Excessive noise on the VDD should be avoided.
The VDD pin has an operational voltage range specification between 1.71V to 3.6V. The internal voltage regulator, which generates current to internal circuitry, operates with an input range from 2.0V to 3.6V. To work with a power supply below 2.0V and to avoid the unnecessary voltage drop, the internal voltage regulator can be bypassed, refer to Figure 1 and Figure 2.
When a power supply is in the range of 1.71V to 2.75V, the VDD and VREG pins can be connected together (Figure 1) so that internal voltage regulator is bypassed. In this configuration, the supply voltage cannot be higher than 2.75V as this is the maximum voltage limit for VREG pin.
When a power supply is higher than 2.75V, it must be connected to the VDD, i.e. configuration as in Figure 2. In this configuration, a separate 0.1 μF decoupli.